1. Field of Invention
This invention relates to a fermentation process; more particularly, this invention relates to a technique for determining a level of foam in the tank based at least partly on an amount of entrained air in a mixture forming part of a fermentation process in a tank, as well as for controlling an amount of defoamer added to the mixture in the tank so as to control the production of foam within the tank.
2. Description of Related Art
There are a number of known processes that use fermentation to create end products in the food and feed industry. For example, the manufacture of L-Lysine (an amino acid essential for human and animal nutrition) can be done through a fermentation process. Ethanol is also an example of a product that is produced through a fermentation process. Depending on the specific fermentation process and results, the process may be continuous (continuous feed and effluent) or the process may be a batch process.
The fermentation process typically involves the introduction of feed stock and nutrients into the batch or continuous process within a fermentation tank or vessel. The process may be open to atmosphere or performed under a controlled pressure in a closed tank.
Additionally, the process may involve the introduction of oxygen, CO2 and other gases, and can include an agitator or other device to circulate the mixture within the fermentation tank.
In certain known fermentation processes, such as the manufacture of L-Lysine, it may be desirable to control the amount foam produced at the top of the fermentation tank due to the fermentation process. Different methods may be used to control the amount of foam at the top of the mixture, including the introduction of surfactants and other defoamer chemicals to the mixture, mechanical removal devices, and controlling the feed stock, nutrients and gas infusion.
Foam at the top of a fermentation tank may be detected through the use of several known methods, including the placement of a foam sensor or level probe within the fermentation tank. The amount of defoamer may be adjusted to control the indication of foam at the sensor. However, this known process is not very accurate, and significant excess defoamer is added to ensure that foam is not indicated in the process, resulting in a waste of such defoamers and added wasteful cost related to the same.
In view of the aforementioned, there is a need in industry applications to be able to detect foam at the top of a fermentation tank, and to reduce the amount of defoamer that is added to ensure that foam is not indicated in the process.